Re: [STLinux Kernel] [PATCH 1/8] serial: st-asc: Ignore the parity error bit if 8-bit mode is enabled

Peter Griffin
2017-01-25T11:02:15Z

On Tue, 24 Jan 2017, Lee Jones wrote:

> The datasheet states:
>
> "If the MODE field selects an 8-bit frame then this [parity error] bit
> is undefined. Software should ignore this bit when reading 8-bit frames."
>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>

Acked-by: Peter Griffin <peter.griffin@linaro.org>

> ---
> drivers/tty/serial/st-asc.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
> index 379e5bd..69e6232 100644
> --- a/drivers/tty/serial/st-asc.c
> +++ b/drivers/tty/serial/st-asc.c
> @@ -287,9 +287,19 @@ static void asc_transmit_chars(struct uart_port *port)
> static void asc_receive_chars(struct uart_port *port)
> {
> struct tty_port *tport = &port->state->port;
> - unsigned long status;
> + unsigned long status, mode;
> unsigned long c = 0;
> char flag;
> + bool ignore_pe = false;
> +
> + /*
> + * Datasheet states: If the MODE field selects an 8-bit frame then
> + * this [parity error] bit is undefined. Software should ignore this
> + * bit when reading 8-bit frames.
> + */
> + mode = asc_in(port, ASC_CTL) & ASC_CTL_MODE_MSK;
> + if (mode == ASC_CTL_MODE_8BIT || mode == ASC_CTL_MODE_8BIT_PAR)
> + ignore_pe = true;
>
> if (port->irq_wake)
> pm_wakeup_event(tport->tty->dev, 0);
> @@ -299,8 +309,8 @@ static void asc_receive_chars(struct uart_port *port)
> flag = TTY_NORMAL;
> port->icount.rx++;
>
> - if ((c & (ASC_RXBUF_FE | ASC_RXBUF_PE)) ||
> - status & ASC_STA_OE) {
> + if (status & ASC_STA_OE || c & ASC_RXBUF_FE ||
> + (c & ASC_RXBUF_PE && !ignore_pe)) {
>
> if (c & ASC_RXBUF_FE) {
> if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) {